In the Western world where the long surgical history of cleft lip repair dates back to 17th century, restoring form and function in the unilateral cleft lip nasal deformity (uCLND) is acknowledged as among the most difficult remaining surgical challenges. Further, compared to the aesthetic aspects of the mature uCLND deformity, the functional implications of uCLND have received limited attention. Although cleft-lip- and/or palate-induced nasal obstruction was first described over 86 years ago, almost no progress has been made to improve treatment outcomes associated with nasal breathing. An estimated 70% of cleft individuals have impaired functional nasal breathing and upwards of 80% ?mouth-breathe?. Structural abnormalities in uCLND create multiple sites of airway obstruction; the inability to accurately identify the most relevant obstructive sites for correction to yield optimal patient outcome is arguably the biggest diagnostic dilemma hindering functional advancement in treating uCLND. Our long-term goal is to restore nasal breathing function to normative levels in post-surgical cleft patients by developing a computational modeling platform to aid surgeons to optimize treatment outcomes. The rationale underlying our application is that once it is known to what extent and severity each of the different sites of airway obstructive deformities impede nasal breathing, post-surgical improvement in nasal function to a normative baseline will be attainable in uCLND patients. Based on the strength of our preliminary data, the following Specific Aims are proposed: [1] Determine effectiveness of current nasal surgical procedure(s) for skeletally mature uCLND patients in restoring nasal function to healthy normative ranges; and [2] Optimize treatment options for uCLND via identification and digital correction of greatest obstructive sites. The culmination of this research will provide a scientific basis for successful treatment of cleft-induced nasal breathing dysfunction because, significantly, our contributions will provide [1] objective evidence for why current interventions may not completely restore nasal function to normative levels, and [2] treatment options with the potential to optimize patient outcomes using computational methods.